1. Technical Field
The present invention relates to a head-mounted display device.
2. Related Art
There is known a head-mounted display device mounted on the head of an observer and used to form a virtual image in a visual field area of the observer. The head-mounted display device is also called head mounted display (HMD). As the head-mounted display device, there are a non-transmissive head-mounted display device that blocks the visual field of a user in a mounted state and a transmissive head-mounted display device that does not block the visual field of a user in a mounted state.
On the other hand, there is known a technique called augmented reality (AR) for additionally presenting information in a real environment using a computer. In order to realize the augmented reality in the transmissive head-mounted display device, the transmissive head-mounted display device causes a liquid crystal display to display only information for additional presentation (e.g., characters and images) for decorating an object present in the real world. A user can bodily sense the augmented reality by visually recognizing both of the information for additional presentation displayed as a virtual image via the liquid crystal display and an outside scene of the real world seen via lenses in front of the eyes.
When the augmented reality is realized by the transmissive head-mounted display device in this way, if a deviation between a position where the information for additional presentation is displayed as a virtual image and the object in the real world increases, the user feels a sense of discomfort. Therefore, there is a demand for grasping the position of the object in the real world when the augmented reality is realized. JP-A-2003-316510 (Patent Literature 1) describes a technique for grasping the position of the object in the real world using a stereo camera configured by a camera with two or more lenses.
In a technique described in Patent literature 1, the camera with two or more lenses is necessary to grasp the position of the object in the real world. Techniques described in JP-A-2011-259341 (Patent Literature 2) and JP-A-2005-122100 (Patent Literature 3) do not take into account that the position of the object in the real world is grasped in the head-mounted display device. Note that such problems occur not only when the position of the object in the real world is grasped using an image of an outside scene acquired by the camera but also when the position of the object in the real world is grasped using information concerning an outside scene (hereinafter referred to as “outside scene information”) acquired by other means (e.g., an infrared sensor).
Therefore, there is a demand for a head-mounted display device capable of grasping the position of the object in the real world using single outside scene information acquiring means. Besides, there is a demand for a reduction in size, a reduction in costs, resource saving, facilitation of manufacturing, improvement of usability, and the like for the head-mounted display device.